1. Field of the Invention
The present invention relates to computers and computer networks. More particularly, the invention relates to securely storing, viewing, and transmitting sensitive information in computerized documents.
2. Background of the Related Art
Most companies and government agencies have a dire need for protecting sensitive information. Encryption, access restriction, and locking documents behind firewalls are some common techniques for protecting sensitive information. Encryption is an effective way for preventing an unauthorized person from viewing the content of a sensitive document. Restricting access of a document to only a few individuals works well with trustworthy individuals. Unfortunately, it is common to find secret documents circulating outside their trusted rings and even in the public media. Identifying the untrustworthy person is often difficult and unpleasant. Firewalls are effective in banning casual outsiders from accessing an organization's network. Firewalls also make it difficult for a savvy computer hacker to break in. Unfortunately, firewalls cannot prevent an insider from copying a sensitive document onto a disk or emailing it to an outsider using a third-party Internet Service Provider (ISP) to avoid tracking.
Digital watermarking is the process of embedding information into a digital signal which may be used to verify its authenticity or the identity of its owners, in the same manner as paper bearing a watermark for visible identification. In digital watermarking, the signal may be audio, pictures, or video. If the signal is copied, then the information also is carried in the copy. A signal may carry several different watermarks at the same time. In visible digital watermarking, the information is visible in the picture or video. Typically, the information is text or a logo, which identifies the owner of the media. In indiscernible digital watermarking, information is added as digital data to audio, picture, or video, but it cannot be perceived as such